This invention relates to wire rope drive mechanisms and more particularly, the invention is related to a bail assembly used as a rope anchor in such mechanisms.
The invention finds particular application in devices such as revolvable power shovels and the like which are particularly adapted to digging horizontally. In shovels of this type the power for both digging and lifting comes principally from the hoist mechanism which continues to take up rope more or less constantly from the starting to the dumping position. A machine of this type is illustrated in detail in U.S. Pat. No. 3,501,034 issued Mar. 17, 1970 to George B. Baron and assigned to the Marion Power Shovel Company, Marion, Ohio.
In connection with power shovels of this general type two hoist ropes can be used, and it is known to use a bail mechanism as an anchor for those ropes forming four rope lines extending to and from the bail. However, the bail mechanisms now in use are presently of a construction which weighs far too much and is far too bulky. Furthermore, in such prior art bail configurations the ropes generally do not leave the bail in a single plane. This means that, as the distance between the bail and the boom point sheaves varies during operation, the ropes must bend and unbend slightly at the point where they leave the bail. Remembering that wire rope is used, it can be seen that such bending will be abusive because it takes place over a grooved radius whch is much smaller than that of the sheave grooves recommended for the particular size wire rope which must be used as hoist rope. Such continuous bending and unbending causes fatigue and eventual deterioration of the rope.
It is, therefore, an object of this invention to provide a bail assembly for wire rope drives wherein four rope lines in relatively close proximity are used and which produces a substantially equal pulling force on each of the rope lines.
It is another object of the invention to provide a bail assembly for a four-rope line, wire rope drive, which permits rope drive operation to take place with minimal bending of the wire rope being caused by the bail assembly.
A further object of this invention is to provide a bail assembly for a four-line wire rope which minimizes the occurrence of slack in the rope and thereby minimizes the occurrence of fouling elsewhere in the rope drive system.
Still another object of the invention is to provide a bail assembly for a wire rope drive utilizing four-rope lines which is capable of properly functioning during highly dynamic operating conditions to maintain its normal moving pattern thereby not becoming cocked and jammed.
It is another object of the invention to provide a bail assembly for a wire rope drive wherein, if necessary, where there is insufficient room for the bail between upper and lower sheaves when the rope drive system approaches its limit the bail assembly contacts those portions of the sheaves which are less easily damaged and in effect allows the bail assembly to operate as part of one of the sheaves.
Still another object of the invention is to provide a bail assembly for a wire rope drive where means are provided for maintaining the ropes in firm contact with the sheaves of the bail assembly as they go through it while allowing the rope freedom of movement without excessive rubbing.